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*NEUROMUSCULAR ASPECTS OF EXERCISE > MODULE 4- Muscle Architecture + Mechanics > Flashcards

MODULE 4- Muscle Architecture + Mechanics Flashcards

1
Q

external brain structures (4)

A

-cerebrum
-cerebellum
-cerebral hemisphere
-brainstem

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2
Q

how is cerebrum split

A

into 2- left + right
-each side is called a hemisphere

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3
Q

what is each side of cerebrum called

A

hemisphere

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4
Q

what is below the cerebrum

A

cerebellum

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5
Q

what is below the cerebellum

A

brainstem

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6
Q

brainstem

A

leads us down into the spinal cord + eventually connects/projects into the muscular system

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7
Q

what is the cerebrum’s surface called

A

neocortex

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8
Q

neocortex

A

the cerebrum’s surface, convoluted into hundreds of folds/grooves

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9
Q

what happens at the neocortex

A

where all the HIGHEST brain functions take place
-cognition
-language
-abstract thinking (where we think about what we do, what it means, etc.)

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10
Q

describe the makeup of the neocortex

A

thin layer of cells about 1.5-4 mm thick

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11
Q

neocortex contains how many neurons

A

25 billion

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12
Q

neocortex contains how many miles of axons

A

62,000 miles of axons

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13
Q

neocortex contains how many synapses

A

300,000,000,000,000

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14
Q

where do the highest cognitive functions take place

A

neocortex

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15
Q

what is the largest portion of the brain

A

cerebrum

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16
Q

where are the 2 hemispheres of the cerebrum connected

A

at the corpus callosum

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17
Q

cerebrum is often divided into how many lobes

A

5 lobes
-each responsible for different brain functions

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18
Q

5 lobes of the cerebrum

A

-frontal lobe
-temporal lobe
-limic lobe
-parietal lobe
-occipital lobe

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19
Q

frontal lobe- functions

A

-problem solving
-memory
-motivation
-judgement
-impulse control
-social + sexual behavior

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20
Q

temporal lobe- functions

A

-emotions
-smelling
-tasting
-perception
-memory
-aggressiveness
-sexual behavior

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21
Q

limbic lobe- functions

A

-regulates emotion + memory
-directly connects the lower + higher brain functions

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22
Q

parietal lobe- functions

A

-processes sensory + spatial awareness
-key component in eye-hand coordination + arm movement

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23
Q

occipital lobe- functions

A

-vision
-object recognition

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24
Q

where is the Wernicke’s area

A

in the back part of the temporal lobe

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25
Q

function of Wernicke’s area

A

-language speaking
-written comprehension

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26
Q

where is the Broca’s area located

A

in the frontal lobe
-usually on the left side

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27
Q

functon of Broca’s area

A

-speech production
-being able to form words + communicate with auditory speech

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28
Q

Wernicke’s area + Broca’s area are connected by what

A

large bundles of nerves called arcuate fasciculus

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29
Q

within the frontal lobe, what is there

A

specific areas that have to do with coordination, cognition, + behavioral processes

-premotor cortex + motor cortex

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30
Q

where are premotor cortex + motor cortex found

A

frontal lobe

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31
Q

motor cortex

A

has to do with planning, control, + execution of voluntary movement
-if I voluntarily send a command to clench my fist, it will be planned then executed through that motor cortex within the frontal lobe

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32
Q

premotor or motor cortex is more anterior

A

premotor cortex

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33
Q

premotor or motor cortex is more posterior

A

primary motor area
-motor cortex

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34
Q

premotor cortex is responsible for what

A

repetitive motions of learned motor skills

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35
Q

primary motor area is responsible for what

A

control of skeletal muscles

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36
Q

what are different areas of the brain associated with

A

different parts of the body

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37
Q

injury to the motor cortex can result in what

A

motor disturbance in the associated body part

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38
Q

cerebellum is connected to what

A

brainstem

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39
Q

brainstem controls what

A

basic life functions

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40
Q

cerebrum is center for what

A

body movement + balance

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41
Q

what does cerebellum do

A

integrates motor + sensory information

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42
Q

what is cerebellum associated with

A

timing of movements + transformation of sensory information into space-time coordinates

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43
Q

thalamus is also called what

A

“the gateway to the cerebral cortex”

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44
Q

thalamus

A

nearly all sensory inputs pass through this to get to higher levels of the brain

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45
Q

basal ganglia

A

a group of nuclei located deep in the cerebral cortex

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46
Q

6 parts of the basal ganglia

A

-caudate
-putamen
-nucleus accumbens
-globus pallidus
-substantia nigra
-subthalamic nucleus

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47
Q

function of basal ganglia

A

-integration of sensory motor centers
-unconscious motor behavior (ex: maintaining muscle tone by sitting with good posture)
-gross body movements

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48
Q

what occurs within the basal ganglion that influences how we move/motor control

A

excitation + inhibition

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49
Q

a patient comes to the neurologist’s office reporting that they’re experiencing falls. the patient is not successful in performing a basic reach-out-and-touch nose with finger test. a follow-up includes a brain scan, which reveals lesions. in which region are the lesions most likely?

a) corpus callosum
b) cerebrum
c) brainstem
d) cerebellum
e) basal ganglia

A

d) cerebellum

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50
Q

2 aspects of spinal cord

A

-dorsal
-ventral

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51
Q

dorsal is sensory/motor

A

sensory

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52
Q

ventral is sensory/motor

A

motor

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53
Q

what is located next to the dorsl root ganglion

A

dorsal horn

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54
Q

dorsal root ganglion

A

bulge/pile/collection of nerves that have to do with sensation

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55
Q

what goes through the dorsal horn

A

afferent sensory information

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56
Q

what travels through the ventral horn

A

efferent signals to muscles + glands via the ventral root

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57
Q

where do motor neurons originate

A

originate in the VENTRAL HORN + comes out to send efferent signals to muscles + glands via the ventral root

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58
Q

afferent

A

sends information in

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59
Q

efferent

A

sends information out

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60
Q

lateral white column refers to what

A

myelination
-white due to a high % of nerves in that area are myelinated

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61
Q

where do we find gray matter

A

cervical + lumbar regions of spinal cord

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62
Q

where are sensory neurons located in spinal cord

A

towards back side of spinal cord

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63
Q

where are motor (efferent) neurons located in spinal cord

A

towards front of spinal cord

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64
Q

what do motor neurons in the anterior gray columns do

A

send axons to innervate skeletal muscle (lower motor neurons)
-this is the FINAL COMMON PATHWAY to the muscle

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65
Q

another name for neurons in anterior gray columns

A

lower motor neurons

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66
Q

what are lower motor neurons constantly bombarded with

A

impulses from the motor cortex, midbrain, medulla, + pons

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67
Q

upper motor neurons

A

supraspinal neurons that form the descending tracts to the alpha motor neurons
-also FINAL COMMON PATHWAY NEURONS

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68
Q

what 2 neurons are final common pathway neurons

A

-lower motor neurons
-upper motor neurons

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69
Q

if you want to do a contraction with your muscles…

A

you have to activate a motor neuron that connects to skeletal muscle

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70
Q

in its simplest form, the descending pathway consists of how many neurons

A

3

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71
Q

3 neurons of the descending pathway

A

-1st order neuron
-2nd order neuron
-3rd order neuron

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72
Q

descending

1st order neuron

A

upper motor neuron

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73
Q

descending

where is the 1st order neuron (upper motor neuron) found

A

motor cortex

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74
Q

descending

where does 1st order neuron (upper motor neuron) connect with 2nd order neuron (interneuron)

A

anterior gray column in the spinal cord

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75
Q

descending

2nd order neuron

A

interneuron

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76
Q

descending

where are 2nd order neurons (interneurons) located

A

spinal cord

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77
Q

descending

describe the axon of 2nd order neurons (interneurons)

A

short axon

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78
Q

descending

3rd order neuron

A

-alpha motor neuron
-somatic motor neuron
-final common pathway neuron
-spinal motor neuron
-lower motor neuron

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79
Q

descending

where are 3rd order neurons located

A

anterior gray column that forms the motor unit

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80
Q

ascending pathway

A

pathway to consciousness (our ability to cognitively think + interpret things)

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81
Q

in its simplest form, the ascending pathway consists of how many neurons

A

3

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82
Q

3 neurons of ascending pathway

A

-1st order neuron
-2nd order neuron
-3rd order neuron

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83
Q

ascending

1st order neuron

A

cell body in posterior root ganglion

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84
Q

ascending

what does the 1st order neuron connect

A

sensory receptor ending + 2nd order neuron in spinal cord

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85
Q

ascending

2nd order neuron does what

A

gives rise to an axon that decussates + ascendings to a higher level of the CNS + synapses with a 3rd order neuron

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86
Q

ascending

3rd order neuron is located where

A

typically in the thalamus

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87
Q

ascending

what does the 3rd order neuron do

A

gives rise to projection fibers that passes to a sensory region of the cerebral cortex

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88
Q

ascending

when neurons are in the brain

A

2nd + 3rd order neurons

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89
Q

presynaptic inhibtion projected by an inhibitory interneuron on an alpha motor neuron is likely which type of neuron?

a) 1st order neuron of the descending pathway
b) 2nd order neuron of the descending pathway
c) 3rd order neuron of the descending pathway
d) 1st order neuron of the ascending pathway
e) 2nd order neuron of the ascending pathway

A

b) 2nd order neuron of the descending pathway

90
Q

what connects muscle fibers

A

3-level network of collagenous connective tissue

91
Q

3 levels of CT connecting muscle fibers

A

-epimysium
-peripmysium
-endomysium

92
Q

epimysium

A

covers the whole muscle

93
Q

perimysium

A

collects bundles of fibers into fascicles

94
Q

endomysium

A

surrounds individual muscle fibers

95
Q

sarcoplasm

A

fluid enclosed within the fiber + sarcolemma

96
Q

sarcolemma

A

excitable cell membrane of muscle fiber

97
Q

myofibril

A

series of sarcmeres, that contain contractile elements

98
Q

what do sarcomeres have

A

thin + thick filaments

99
Q

a single skeletal muscle fiber contains many ____

A

myofibrils

100
Q

what is found within the myofibril

A

sarcomeres

101
Q

sarcomere

A

the basic functional unit for each myofibril

102
Q

how are sarcomeres aligned within the myofibril

A

in series (one after the other)
-thousands of sarcomeres making up the myogibril

103
Q

describe myofibrils in terms of muscle fiber

A

myofibrils run the length of the muscle fiber + thus vary from 1-400 mm in length + 1 mm in diameter

104
Q

a 10 mm myofibril contains how many sarcomeres in series

A

4000

105
Q

sarcomere definition

A

the longitudinally repeating pattern of dark + light bands (striations) from z disk to z disk

106
Q

thick + thin filaments are called ____

A

myofilaments

107
Q

how many thin filaments connect to each z band

A

3000-6000

108
Q

thick filaments consist of what

A

myosin

109
Q

thick filaments terminate in ____

A

large globular heads

110
Q

thin filaments include what

A

actin + 2 regulatory proteins (toponin + tropomyosin)

111
Q

excitation-contraction coupling

A

process of converting a muscle fiber AP into muscle fiber force

112
Q

excitation-contraction coupling steps

A

AP propagation along muscle fiber ->
AP propagation down T-tubule ->
AP coupling to the change in calcium conductance of the SR (sarcoplasmic reticulum) ->
release of calcium from SR ->
reuptake of calcium into SR ->
calcium binding troponin ->
interaction of contractile protein

113
Q

ATP stands for

A

adenosine triphosphate

114
Q

contractile force is produced by the interaction between what

A

thick + thin filaments

115
Q

cross bridge cycle

A

mechanism of sarcomere shortening during contraction
-involves cyclical attachment + detachment of myosin heads to adjacent thin filaments (actins)

116
Q

what 2 things are required by cross bridge cycle

A

-ATP
-Ca2+

117
Q

sliding filament hypothesis

A

thick + thin filaments slide past each other in cross bridge cycle

118
Q

who came up with the sliding filament hypothesis

A

Huxley et al. 1950s

119
Q

steps to muscle contraction (cross bridge)

A

myosin heads hydrolyze ATP + become reoriented + re-energized ->
myosin heads bind to actin, forming cross bridges ->
myosin cross bridges rotate toward center of sarcomere (powerstrike) ->
as myosin heads bind ATP, the cross bridges detach from actin

120
Q

isotonic

A

muscle length is changing

121
Q

isometric

A

muscle length isn’t changing

122
Q

2 types of isotonic contractions

A

-concentric
-eccentric

123
Q

concentric: muscle torque or load is greater

A

muscle torque > load

124
Q

concentric: muscle shortens/lengthens

A

shortens

125
Q

concentric: load is lowered/lifted

A

lifted

126
Q

eccentric: muscle torque or load is greater

A

muscle load > torque

127
Q

eccentric: muscle shortens/lengthens

A

lengthens

128
Q

eccentric: load is lowered/lifted

A

lowered

129
Q

eccentric/concentric requires the most force

A

eccentric

130
Q

slower you move, more/less force

A

MORE

131
Q

faster you move, more/less force

A

LESS

132
Q

what does movement require

A

unequal muscle + load torques

133
Q

isometric ratio of (muscle / load) torque

A

muscle / load torque = 1

134
Q

concentric ratio of (muscle / load) torque

A

muscle / load torque > 1

135
Q

eccentric ratio of (muscle / load) torque

A

muscle / load torque < 1

136
Q

concentric/eccentric requires more muscle activation to achieve a given muscle froce

A

concentric

137
Q

electromyography (EMG)

A

an extracellular recording technique that measures the change in the potential difference in the extracellular space due to the activation of many motor units

138
Q

what does EMG indicate

A

when a muscle is active

139
Q

what does EMG procide an estimate of

A

the force produced by the contraction

140
Q

EMG is a _____ comparison

A

extracellular space comparison

141
Q

what does EMG suggest

A

fatigue-related changes in motor unit activity

142
Q

how does EMG estimate force production by a muscle?

a) EMG tells us about how much a single motor unit is discharging action potentials, which tells us about how much force that motor unit produces
b) EMG describes the sum of the motor unit action potentials, which increases with greater force
c) EMG will be reduced in amplitude as target force increases

A

b) EMG describes the sum of the motor unit action potentials, which increases with greater force

143
Q

study “fluctations in acceleration during voluntary contractions lead to greater impairment of movement accuracy in old adults” was done by which professor

A

Evangelos Christou

144
Q

study

study- to assess the effect of movement velocity on the relation between FLUCTUATIONS IN ACCELERATION + the ABILITY TO ACHIEVE A TARGET VELOCITY during voluntary contractions performed by young + older adults

A

15% MVC
-6 movement velocities

145
Q

study

EMG amplitude increased with ____

A

velcoity
-BUT ONLY FOR CONCENTRIC CONTRACTIONS

146
Q

study

for study on acceleration +target velocity, were concentric + eccentric results statistically significant

A

concentric were statistically significant
-eccentric weren’t

147
Q

study

what did study find for concentric + eccentric contractions

A

more steadiness with slower contractions vs faster contractions for BOTH

148
Q

study

does velocity affect steadiness/force fluctuations for eccentric contractions

A

NO
-average EMG/muscle activity are the same

149
Q

study

given there wasn’t a change in EMG for eccentric, but there was for concentric, what does this suggest

A

sarcomeres are not shortening for eccentric, but they are for concentric

150
Q

study

fluctuations in acceleration increased with velocity for eccentric/concentric

A

BOTH contractions

151
Q

study

standard deviation of acceleration increased with movement velocity for eccentric/concentric

A

BOTH contractions

152
Q

study

which can explain why EMG does not change with velocity during eccentric contractions?

a) gravity will promote the mechanical separation of thin + thick filaments
b) gravity will not promote the mechanical separation of thin + thick filaments
c) this lack of EMG change is not consistent in the rest of the literature (just this study)
d) false statement: EMG does change with velocity during eccentric contractions

A

a) gravity will promote the mechanical separation of thin + thick filaments

153
Q

the force a muscle exerts depends on what 3 things

A

-the contractile properties of the activated muscle fibers
-the arrangement of the fibers in the muscle
-the attachment sites of the muscle on the skeleton

154
Q

mechanical properties can be described at what 3 levels

A

-single fiber
-whole muscle
-joint

155
Q

SINGLE FIBER LEVEL

what is force output related to

A

the number of cross bridges occurring at the same time
-the more cross bridges you have engaged, the more force you should be outputting
-this is why when you lift a lot of weight you lift slowly so that you don’t miss any cross bridges

156
Q

SINGLE FIBER LEVEL

as the length of the muscle changes + the thick + thin filaments slide past each other, what happens

A

the number of actin-binding sites available for the cross bridges changes

157
Q

SINGLE FIBER LEVEL

what does tension mean in terms of muscle

A

the number of crossbridges that can be bound

158
Q

SINGLE FIBER LEVEL

when is tension maximal

A

at intermediate lengths
-at middle segment

159
Q

SINGLE FIBER LEVEL

when does tension decrease

A

at shorter + longer lengths

160
Q

MUSCLE LEVEL

force output is related to what 2 things

A

-an active component
-a passive component

161
Q

MUSCLE LEVEL

active component of force output

A

-voluntary activation
-number of cross bridges occurring concurrently

162
Q

MUSCLE LEVEL

passive component of force output

A

-no voluntary activation
-connective tissues

163
Q

MUSCLE LEVEL

where is tension maximal

A

at longer lengths

164
Q

MUSCLE LEVEL

why is tension maximal at longer lengths

A

because of the contribution of active + passive components; sum of active + passive components

165
Q

JOINT LEVEL

where is tension maximal

A

at intemediate lengths
-decreases at shorter + longer lengths

166
Q

does joint level tension relationship correspond to whole muscle relation

A

NO
-rather, it mimics the single fiber force-length relation

167
Q

how do muscle fibers that do not span the length of the muscle contribute to force produced by the muscle?

a) force-generating capabilities can jump between fibers wtihin a muscle
b) force is transmitted laterally via connective tissue
c) most muscle fibers within a muscle do not actually contribute to force
d) this is not the case in all humans; most muscle fibers span the entire length of the muscle

A

b) force is transmitted laterally via connective tissue

168
Q

contractile proteins

A

thick + thin filaments

169
Q

what are contractile proteins (thin + thick filaments) connected to

A

cytoskeletal proteins (desmin, skelemin, etc.)

170
Q

how are contractile proteins connected to cytoskeletal proteins

A

through connective tissue

171
Q

cytoskeletal proteins involved in longitudinal transmission

A

-titin
-nebulin
-MARP
-MLP

172
Q

cytoskeletal proteins involved in lateral transmission

A

-titin
-dystrophin
-integrins

173
Q

cytoskeletal proteins involved in linking the 2 modes of force transmission (longitudinal + lateral) + play a role in both processes

A

-desmin
-alpha-actinin

174
Q

what is special about titin

A

involved in both lateral + longitudinal transmission
-shares information between them

175
Q

a loss in lateral force transmission appears to lead toward what

A

sarcolemma damage + membrane disruption

176
Q

can you think of a disease that involves the disruption of connective proteins?

A

duchene’s muscular dystrophy

177
Q

what protein is involved in duchene’s muscular dystrophy

A

dystrophin
-this is the protein with the problem

178
Q

what do dystrophin + integrins do

A

act like rivets + ties that couple the intracellular matrix to the extracellular matrix
-this prevents shear stress from damaging the sarcolemma

179
Q

what happens when there is loss of dystrophin + integrins in muscular dystrophies

A

weakens the connection between the intracellular + extracellular matrices
-this renders individual fibers to be more susceptible to damage from shear forces

180
Q

duchenne’s muscular dystrophy is what type of disorder

A

genetic

181
Q

duchenne’s muscular dystorphy is characterized by what

A

progressive muscle degeneration + weakness

182
Q

how many types of muscular dystrophy are there

A

9

183
Q

what is duchenne’s msuscular dystrophy caused by

A

absence of dystrophin
-causes failure to keep muscle cells intact

184
Q

single fiber level

as cross bridges slide past each other at SLOW VELOCITIES, why is their reattachment is faster

A

gravity is helping
-it is a mechanical separation + no need for ATP

185
Q

single fiber level

as crossbridges slide past each other at FAST speeds, what happens

A

the binding sites are missed as the thick
+ thin filaments slide past eachother

186
Q

muscle level

for shortening contractions, force output increases/decreases with velocity

A

decreases

187
Q

muscle level

during shortening contractions, force ouput increases/decreases with velocity + why

A

decreases
-because some binding sites are missed as the thick + thin filaments slide past each other at a fast speed

188
Q

joint level

during shortening contractions, force output increases/decreases with velocity

A

decreases
-the binding sites are missed as the thick + thin filaments slide past each other at a fast speed

189
Q

joint level

during lengthening contractions, force output increase/decreases with velocity

A

IS CONSTANT with velocity
-maybe this is due to different activation of muscles during lengthening contractions

190
Q

in series

A

muscle fibers placed one after the other

191
Q

in series ROM

A

greater ROM

192
Q

in parallel

A

muscle fibers arranged next to each other

193
Q

in parallel ROM

A

less ROM
-but greater force generation

194
Q

in pennation angle

A

maximize number of fibers in a given volume + thus force capacity

195
Q

true/false: the deltoid muscle has multiple pennation angles, which enhances maximum force output

A

true

196
Q

motions at joints are ____

A

rotary
-because joint is an axis of rotation

197
Q

what type of forces do muscle produce

A

linear

198
Q

rotary torque equation

A

rotary torque = linear force x moment arm

199
Q

moment arm

A

distance from axis of rotation

200
Q

force length relationship joints

A

anaogy- if I open a door right next to the hinge, the amount of force I have to produce to be able to open the door is a long more than if I move out + create a longer moment arm

201
Q

shorter moment arm results in…

A

better involvement through ROM

202
Q

longer moment arm results in…

A

greater muscle torque generation

203
Q

why do we have a knee cap?

A

to increase moment arm

204
Q

what type of bone is patella

A

seismoid

205
Q

patella

A

-very important structurally
-helps to increase lever arm for knee movement
-if it doesn’t move properly, you must go in for surgery

206
Q

stretch-shorten cycle

A

a method to stretch + store more energy
-bigger stretch results in more elastic energy stored
-SPRING-like mechanism

207
Q

stretch-shorten cycle

pre-stretch causes what

A

eccentric lengthening of muscle, which builds tension (think rubber band)

208
Q

stretch-shorten cycle

longer pre-stretch =

A

less tension

209
Q

stretch-shorten cycle

increasing speed of coil compression or force applied =

A

spring jumping higher or further (“rate of loading”)

210
Q

stretch-shorten cycle fast speed

A

<250 ms

211
Q

stretch-shorten cycle slow speed

A

> 250 ms

212
Q

work

A

product of force + the displacement of a body along the same line the force is acting

213
Q

positive work

A

when force has a component in the same direction as the displacement of the body

214
Q

negative work

A

when force has a component in the opposite direction to the displacement of the body

215
Q

energy

A

ability of a body to perform work

216
Q

power

A

performing work over a certain amount of time
-measures speed with which work is performed
-product of force and velocity of displacement of a body in the direction of the force

217
Q

gross efficiency

A

how efficient a system is
-mechanical work/metabolic work

218
Q

what is the most common method to measure metabolic energy

A

rate of oxygen consumption

219
Q

2 joints is better/worse than 1 joint

A

BETTER
-when the movement of 2 joints is coupled, better + more efficient for coordination

220
Q

the shortening velocity of a 2 joint muscle is more/less than that of a 1 joint synergist

A

LESS
-this is due to redistribution of muscle torque, joint power, + mechanical energy throughout the limb

221
Q

mechanical factors that influence force generation

A

-length
-speed
-moment arm
-number of joints crossed

*NEUROMUSCULAR ASPECTS OF EXERCISE (4 decks)

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